At present, many soldiers don’t have communications radios because the hardware is too expensive. Buying 2-way radios from Radio Shack before deployments solved that problem for some soldiers, but insecure communications created others. On the high end, the US military’s JTRS program is expected to create radios that are much better at working together, and much easier to upgrade. As one might expect, however, the hardware appears to be on track to be more expensive, in return for that improved performance.
The US Defense Advanced Research Projects Agency’s Wireless Network after Next (WNaN) program aims to shift the approach used to design these military wireless networks. It also intends to use inexpensive, high-volume, commercial off the shelf hardware components. They would be combined with adaptive wireless network software operating over densely-deployed, low-cost wireless nodes, with the aim of putting a reliable communications radio into the hands of every soldier. How could that work?
WNAN: The Concept
Right now, military wireless networks are designed for radio range. Instead, DARPA wants to employ more of an ad-hoc swarm strategy, and design for node density. The idea is that with more WNaN components on the ground, it becomes easier to find other nodes in range and link to them, creating reliable local networks.
Those ad-hoc meshes could then be combined with more expensive gear that connects the whole network back to HQ. The result? Everyone has an inexpensive radio, and the group still has full radio range and performance.
WNaN has 2 complementary components. When integrated together and deployed, DARPA hopes that these 2 components will create a distributed, intelligent network entity that is more than the sum of its parts.
The first focus area (WANN) is low-cost, multi-channel, spectrum-agile, MIMO-capable wireless nodes, built with inexpensive RF circuit technology. MIMO technology can already be found in some homes these days, where advanced wireless Internet routers use multiple antennas at both the transmitter and receiver for better performance.
The second focus area (WAND) is a network with densely deployed low-cost wireless nodes, and adaptive network layers that mitigate the shortcomings of any individual nodes by leveraging their rich interconnection. A philosophy that’s very much like the Internet itself.
Raytheon BBN identifies several key aspects of their WNaN efforts:
Dynamic Spectrum Access (DSA). eliminates frequency pre-planning and fixed frequency assignments, in favor of DSA techniques that sense which spectrum is in use and which is available. It’s backed by strict policy compliance checking, in order to use the right spectrum at the right time.
Multiple Transceivers. WNaN’s MAC and network protocols are designed from the beginning to operate efficiently over 1, 2, 4, 6, or even more channels. Complements DSA.
Disruption Tolerant Networking. Today’s networking protocols all drop packets immediately if any node along the path loses the route to the destination. In WNaN, the nodes store packets temporarily during link outages. In field experiments, this DTN implementation sitting under the standard IP stack has delivered 100% of the traffic in situations where traditional IP-networking delivered less than 10%. Because DTN sits under the standard stack, all current IP applications still work.
Content Based Access. Instead of having to know the exact filename, transport protocol, and node, CBA techniques that allow users to query the network to find information, and some critical, often used data like maps can be automatically pre-placed around the network.
Multicast Voice with Quality of Service. Configurable call groups that can support the kind of quality and reserved network capacity required for voice communications, or ensure that high-priority data makes it through demands on the network.
Energy saving portability. The WNaN protocols are designed for small handheld devices, and targeted for embedded operating systems and processors. They include energy conserving capabilities.
Contracts and Key Events
Work will be performed in Cambridge, MA. The contract is managed by the Air Force Research Laboratory/RKID in Rome, NY (FA8750-11-C-0201 PO0001).
Sept 23/10: Raytheon BBN Technologies Corp. in Cambridge, MA received a $12.5 million contract modification. They will provide additional tasking to support the DARPA and Army experiments at Fort Benning, GA, and will add the software radio waveform to the WNAN radio. At this time, $2.6 million has been committed by the US Air Force Research Laboratory/RIKF in Rome, NY (FA8750-07-C-0169; PO0013).
Feb 1/10: Raytheon BBN Technologies announces a successful WNaN test, sending voice and data across a wireless mobile ad hoc network that was in a constant state of flux. The experiment used 10 WNaN mobile handheld radios that participated in multiple, simultaneous call groups, faced interference from hostile signals, and had to continue operation even when large numbers of warfighters tried to use the channel at once. Automatic frequency assignment and reassignment, network scaling techniques, and vice relay over different network radios were also tested.
Aug 3/09: Alion Science and Technology in McLean, VA receives a $7.8 million contract to esearch and identify RF spectrum management and modeling issues associated with WNAN and make recommendations to the US Army Spectrum Management Office for effectively addressing spectrum issues associated with WNAN.
The period of performance for the contract runs June 26/09 through June 25/12. The work is sponsored by the Defense Modeling and Simulation Office, under the Modeling and Simulation Information Analysis Center (MSIAC) contract vehicle (N61339-03-D-0300). Read “Alion to Provide Modeling and Simulation to Help Ease Spectrum Overcrowding” for more in-depth coverage of this contract’s WNAN connections and Alion’s activities.
June 2/09: BBN Technologies in Cambridge, MA announces $11.3 million in funding for WNaN work, under an Air Force Research Laboratory contract. Under this award, BBN will develop and test a hardened virtual network infrastructure with higher scalability and will demonstrate the technology on a M/A-COM radio. Following a 20 node demonstration in August 2009 and a September test against jamming devices, BBN and M/A-COM will deliver an additional 50 nodes per week over a 7-week period.
December 2008: BBN conducts a field demonstration of multihop, packetized voice transmission across groups of hand-held WNaN radios. The demonstration also showed WNaN’s integration with U.S. Army command and control situational awareness and chat applications, dynamic spectrum access (which allows the nodes to avoid interfering with non-cooperative signals), disruption tolerant networking (for delivering video traffic even when multiple paths get disrupted), and interoperation with existing radios. Source.
Additional Readings
* DARPA – WNaN project page.
* Raytheon BBN – Wireless Network After Next
* Network World (Nov 1/07) – DARPA looks to adaptive battlefield wireless nets
* FBO Solicitation (March /07, #SN07-26) – A — Wireless Network after Next (WNaN) Adaptive Network Development (WAND) API Technical Interchange Meeting (TIM)
